The field of the present disclosure relates generally to semiconductor technology and, more specifically, to a dual-band infrared detector capable of detecting radiation in both short wavelength and medium wavelength infrared spectral bands.
At least some known photodetector devices are formed from a semiconductor material, such as Indium Arsenide Antimonide (InAsSb). InAsSb has a high quantum efficiency, enhanced dark current performance in certain spectral bands, and a low direct energy gap when compared to other Group III-V semiconductor materials. As such, InAsSb is capable of effectively detecting radiation in the medium wavelength infrared spectral band, which generally facilitates detecting radiation from the thermal infrared signature of an object, for example. However, an inherent lattice mismatch between InAsSb and known substrates arises when attempting to lower the detection range of InAsSb to a shorter spectral band. The inherent lattice mismatch causes defects to be formed in the photodetector device. Moreover, using materials sensitive to radiation in only the medium wavelength infrared spectral band to detect radiation in the short wavelength infrared spectral band, for example, results in high dark currents and prevents medium wavelength radiation from reaching the medium wavelength infrared spectral band.
At least some known semiconductor materials are capable of performing dual-band infrared detection. Exemplary semiconductor materials capable of dual-band infrared detection include, but are not limited to, Mercury Cadmium Telluride (HgCdTe) detectors, quantum well infrared photon (QWIP) detectors, and Indium Arsenide/Gallium Antimonide (InAs/GaSb) superlattice detectors. HgCdTe detectors are generally grown on a relatively expensive Cadmium Zinc Telluride (CdZnTe) substrate, thereby limiting the use of HgCdTe detectors in large arrays, or in single use applications. QWIP detectors have a narrow spectral response and a low operating temperature, which makes QWIP detectors generally unsuitable for applications requiring high frame rates. InAs/GaSb superlattice detectors have a high dark current performance due to surface leakage, when compared to other known photodetector devices. Moreover, Indium Gallium Arsenide (InGaAs) effectively detects radiation in the short wavelength infrared spectral band, but is generally unable to detect radiation in other spectral bands because of its high bandgap.